I mainly use cheats (all learned here!) for building, or to fix something that has gone wrong. (I haven't played any challenges yet, and if I someday do I wouldn't use cheats).
Recently I learned make needs static (thanks Esther!) and I've mainly used it when I want to play characters that have needed constant resetting. That cheat has become a bit of a slippery slope for me, but it 'fixes' me being impatient with dealing with needs that you wouldn't discuss in polite company. Only so much time to play in a day, and I sometimes get annoyed with the repetitiveness of their needs. If I can play with out having to 'go', then my Sims should too, they can wait until after I shut down the game! I don't use make needs static all of the time, but the game often loses all it's fun for me when all my character is doing is---> wake, eat, potty, bathe, work, eat, potty, clean house, bathe, sleep---> repeat until weekend, when she's lucky to get to go to the library, have a swim, and turn down party invitations to sleep, so she can begin the cycle again on Monday well rested for work.
I use the family funds cheat for building, and for my little kid's builds. We call it "winning the lottery". Also I've just used move objects for the first time, and place frieze in my honking big mansion build to make the staircase.